Close linkage of the two keratin gene clusters in the human genome

Mapping studies of functional keratin genes in the human genome have localized most of the acidic keratin genes to chromosome 17q12-q21 and the basic keratin genes to chromosome 12q11-q13. Within the acidic keratin locus two clusters were identified, one containing the genes for K15 and K19, the other the genes for K14, K16, and K17. The relative positions and the distance between the two clusters have not been determined previously. In this paper we describe our analysis of P1 clones containing multiple acidic keratin genes, which were studied using restriction analysis and Southern blot hybridization with PCR-amplified probes specific for functional human keratin genes 15, 17, and 19. Our results show that the two clusters are very closely linked to each other, within a 55-kb region in the human genome. The genes are organized 5' to 3' in the following order: 5'-K19-K15-K17-K16-K14. Between K15 and K17 at least one additional, unidentified keratin gene is present.